1. Field of the Invention
The invention generally relates to a pet food for use in a comprehensive weight management system for companion animals. More particularly, the weight management system includes two stages: a weight loss stage (stage I) and a weight maintenance stage (stage II). Stage I involves a pet food comprising a high protein, low calorie daily diet that includes a functional ingredient, which further modulates metabolism and builds lean body mass in companion animals. Stage II involves a pet food comprising a low calorie daily diet that maintains the leaner weight of the animal and improves health for the life of the animal.
2. Related Art
In westernized societies the most prevalent form of malnutrition in humans is over-consumption of calories resulting in excess body fat. Studies have shown that greater than 20-30% of dog and cat populations are overweight or obese (over-fat). Obesity in domesticated dogs and cats has been linked to the development of numerous diseases including renal failure, diabetes, and arthritis. Overweight dogs have an increased risk of developing transitional cell carcinoma of the bladder. Further, it is well established that obesity is a predisposing factor to idiopathic hepatic lipidosis in cats, however, their inability to convert dietary C18 essential fatty acids into long chain fatty acids creates a need for dietary consumption of 20 carbon long chain fatty acids. Such a dietary requirement leaves cats extremely vulnerable to weight disorders and weight-associated diseases such as diabetes (Appleton et al., 2000).
Obesity generally is considered present when body weight of the companion pet is 15% or more greater than optimum, which is the point at which health problems begin increasing with increasing weight. Generally speaking, the incidence of obesity in domestic animals increases with age. Similar to humans, as a dog ages, body fat increases, and lean body mass decreases. However, obesity commonly goes unnoticed by the animal's owner and, thus, poses a life-threatening problem to domesticated animals.
Some pet food compositions formulated to prevent or treat obesity in animals have been described. U.S. Pat. No. 6,071,544 teaches that a specific combination of long chain conjugated fatty acids (0.2 to 1.5 weight % of dry matter) together with up to 50% protein promotes weight loss in cats. A diet greater than about 16% by weight of animal-based protein is taught to reduce body fat in geriatric dogs (WO 00/51443). However, U.S. Pat. No. 5,141,755 teaches that non-meat based animal fats in a high protein, high farinaceous diet provides an ovo or lacto-ovo nutritionally balanced pet food product. U.S. Pat. No. 4,892,748 describes a low calorie dog treat that is comprised primarily of cellulose, a β-1,4-glucan that affords no nutritional value to the animal.
Further, a pet food composition that improves several clinical indications (i.e., BUN, creatinine, phosphorous, CO2 and triglyceride levels) in animals with renal disease is described in U.S. Pat. No. 6,039,952 and U.S. Pat. No. 6,306,442. This pet food includes from about 10 to about 32% crude protein, from about 8 to about 20% fat, from about 3 to about 25% total dietary fiber, and fermentable fibers which have an organic matter disappearance of 15 to 60% when fermented by fecal bacteria for a 24 hour period, the fibers being present in amounts from about 1 to 11 weight percent of supplemental total dietary fiber. The composition is taught to provide adequate protein, has low phosphorus levels, improves metabolic buffering, and lowers blood triglyceride levels in the animal.
Similarly, diets disclosed for the treatment of human obesity have included compositions such as a concentrate that consists entirely of non-animal natural components, a lack of simple sugars and a flour comprising of at least 50% protein, of less than 15% carbohydrates and of 35 to 50% plant fiber for use in the preparation of foods such as bakery products (U.S. Pat. No. 4,737,364; EP 965278 A1). Such diets are not completely without credence because hypertension, and, thus, risk of developing cardiovascular disease, in obese patients has been linked to disturbances in carbohydrate metabolism (Nobels et al., 1989).
However, low calorie diets comprising increased ratios of amino acids to carbohydrates, such as the diet taught in U.S. Pat. No. 4,009,265, cause increased blood urea nitrogen (BUN) concentrations. Urea is a by-product of protein or amino acid catabolism and thus is directly related to the amount of protein in a diet. The kidneys function to remove urea from the plasma, and in this regard high protein diets place an unusual burden on the kidneys which can lead to severe consequences over time including the development of azotemia or uremia.
Also symptomatic of high protein diets is the potential to induce ketosis, a condition that is shared in humans and dogs. Ketosis is a pathological condition in which the brain consumes ketone bodies as its major fuel source and is a diagnostic for diabetes mellitus. For example, urine abnormally high in ketone bodies is expected after a prolonged fast. However, this metabolic shift is undesirable and also leads to severe renal damage if experienced over long periods of time.
Natural products derived from plants and food are frequently employed as effective drugs, and in recent years there has been an increased interest in the analysis of these natural products, especially where a clinical benefit is claimed. For this reason, functional ingredients which include secondary metabolites of plant and animal origin, are often added to foods in order to effect a desired metabolic response. For example, EP 646325A1 describes a pet food comprised of at least 30% by weight of indigestible dextrin that demonstrates obese-improving effects by controlling blood-sugar levels and insulin secretion in dogs and cats.
Several patents to the Wisconsin Alumni Research Foundation describe the use of certain prepared conjugated linoleic acid (CLA) isomers, namely 9-cis, 11-trans CLA and 10-trans, 12-cis CLA, to alter body fat levels and lean body masses without a effect on body weight (U.S. Pat. No. 6,020,378; U.S. Pat. No. 5,760,082; U.S. Pat. No. 5,554,646; and U.S. Pat. No. 5,855,917). In fact, U.S. Pat. No. 5,428,072 describes that incorporation of CLA into animal feed increased efficiency of feed conversion leading to a greater weight gain in the CLA supplemented animals. Further, these same CLA isomers, denoted therein as c9,t11 and t10,c12, are taught in several patents owned by Conlinco Inc., as the biologically active isomers of CLA and synthetic preparation methods that allow for the enrichment of the t10,c12 linoleic acid isomer and uses thereof are described (U.S. Pat. No. 6,410,761; U.S. Pat. No. 6,333,353; U.S. Pat. No. 6,015,833; U.S. Pat. No. 6,380,409; U.S. Pat. No. 6,214,372; U.S. Pat. No. 6,060,514; U.S. Pat. No. 6,242,621; U.S. Pat. No. 6,225,486).
U.S. Pat. No. 5,962,043 teaches jojoba seed meal as a nutritional supplement in animal feed, particularly for companion dogs, to promote weight loss. Simmondsin served as the active or functional ingredient in the feed that, based on previous research, results in an associated reduction in food intake and retardation of growth. These formulations include high fat and high caloric density to ensure palatability.
U.S. Pat. No. 6,204,291 teaches dietary supplementation with L-carnitine, a naturally occurring acid also known as β-Hydroxy-γ-trimethylaminobutyrate, in dog food to promote weight loss. Carnitine is found in the body and is enzymatically combined with fatty acids to facilitate their transportation through mitochondrial membranes, thus aiding in fatty acid metabolism (Yalkowsky, S. H., 1970). Oral administration of L-carnitine for obesity in mammals has been described in U.S. Pat. No. 3,810,994. It also has been implicated in improvements in myocardial contractility and systolic rhythm in congestive heart failure, it has been administered in cases of cardiac arrythmia (U.S. Pat. No. 3,830,931 and U.S. Pat. No. 3,968,241), and for increasing high density lipoproteins levels (U.S. Pat. No. 4,255,449).
Prior to the present invention, diet solutions have not provided a comprehensive approach in addressing the issues of weight management. Most diets simply lower caloric density, increase total carbohydrates by increasing fiber, which leads to reduced palatability, thereby creating a diet that leaves the animal hungry and, sometimes, induces lean body (i.e., muscle) loss.
The present invention provides a long-sought after comprehensive weight management system for companion animals, particularly obese animals, for treating and preventing obesity through dietary intervention. The present invention also increases and maintains the lean body mass of companion animals as well as enhances satiety, decreases voluntary food intake, decreases BUN levels and reduces the risk of ketosis in the animal.